Ultrasound assessment of elbow enthesitis in patients with seronegative arthropathies

Enthesopathy is an evolving area for applied clinical research. MRI is the gold standard in the diagnosis of elbow joint pathology, but recent reports indicate that ultrasound imaging is more sensitive and accurate than MRI in detecting enthesopathy of the heels and knees. Too many patients are under-diagnosed and/or misdiagnosed because the early pathological changes of enthesitis in the different types of seronegative arthropathies are not detected.

This study was undertaken to describe the ultrasound features of elbow enthesitis in patients with seronegative arthropathies.

We studied 38 diseased elbows in 38 patients with spondyloarthropathies (26 men and 12 women, mean age 32 years). All had elbow enthesopathy without typical conventional radiographic findings. Patients with histories of degenerative changes and/or local steroid injections were excluded. An HDI 3000 ATL ultrasound machine was used with a 5-12 MHz linear transducer to examine the affected elbow joints. The elbows of 10 normal healthy individuals were examined as normal controls. The patients were examined in the supine position with the elbow flexed 30°-50°. Longitudinal and transverse scans were obtained of the radiohumeral joint, the ulnahumeral joint, and the olecranon fossa. Two independent observers unaware of the clinical diagnosis read the ultrasound images and assessed the collateral ligaments, intratendinous echogenicity, tendon calcification, tendon thickness, presence of fluid, synovial proliferation, and bony changes. The reliability of the sonographic images was assessed by review of video recordings of the ultrasound examinations.

Ultrasound revealed loss of the fibrillar echopattern (100 %), lack of a homogenous pattern with loss of the tightly packed echogenic dots (100 %), peritendinous edema with flaring of the tendon margins (84.2 %), irregular fusiform tendon thickening (100 %), and hyperechoic intratendinous lesions with ill-defined focal defects (18.4 %). Ultrasound also detected intratendinous calcifications of both the common extensor and common flexor tendons (52.6 %). Bony erosions were seen at the tendon insertions into the lateral epicondyles (13.15 %).

Ultrasonographic features of elbow enthesitis differed from those described in knee and heel enthesitis. Ultrasound clearly showed early signs of tendon calcification, tendon edema, peritendinitis, and bony entheseal erosions. However, in elbow enthesitis the early bone erosion was associated with bone marrow edema, and the common extensor tendon was diffusely thickened. Ultrasound is a reliable, reproducible bedside imaging procedure. It improves the documentation of disease activity, progression, and treatment responses in patients with spondyloarthropathies. We recommend its use for the diagnosis and post-treatment follow-up of patients with enthesitis and seronegative spondyloarthropathies.